Apparatus and method for providing uniform flow of gas

A gas distribution apparatus, comprising:

• a spiral gas delivery channel recessed in a back side of a gas distribution plate, the recessed gas delivery channel having an inlet end, an outlet end and a length, the gas delivery channel having a plurality of apertures spaced along the length extending through the gas distribution plate to a front side of the gas distribution plate so that gas flowing through the gas delivery channel can pass through the apertures exiting the gas distribution plate;
• a back cover on the back side of the gas distribution plate, the back cover covering the recessed channel;
• an inlet connected to the inlet end of the gas delivery channel through the back cover, the inlet connectable to a gas source, wherein a flow of gas is controllable by a gas valve in communication with the inlet;
• an outlet connected to the outlet end of the gas delivery channel through the back cover, the outlet connectable to a vacuum source, wherein vacuum pressure through the outlet is controllable by an outlet valve to provide a reduced pressure at the outlet;
• and
• a controller to regulate the flow of the gas through the gas delivery channel and into a process chamber by opening and closing the outlet valve during gas delivery and gas purging to control the flow of gas through the apertures along the length of the channel.

A gas distribution apparatus, comprising:

• a plate having a front surface and a back surface;
• a first recessed channel formed in the back surface of the plate and extending from a central region of the back surface to an outer peripheral region of the back surface;
• a second recessed channel formed in the back surface of the plate and extending from the central region of the back surface to the outer peripheral region of the back surface;
• a first plurality of apertures along the first recessed channel, each of the first plurality of apertures extending through the plate from the front surface to the first recessed channel;
• and
• a second plurality of apertures along the second recessed channel, each of the second plurality of apertures extending through the plate from the front surface to the second recessed channel, wherein
• the first recessed channel and the second recessed channel are intertwined, and
• a surface of the first recessed channel and a surface of the second recessed channel each further comprise an upper portion that is disposed between a lower portion and the back surface, and the lower portion having a rounded shape.